Proposals to build a US-style super-dairy in mid-Wales for up to 1,000 cows have been given to go-ahead, against the advice of a public inquiry inspector.

Planning Minister Carl Sergeant said he did not accept the recommendation to refuse the scheme at Lower Leighton Farm near Welshpool due to the economic benefits it would bring.

On Thursday campaigners called the decision “a dark day for Wales and for Welsh dairy farmers.”

Farmer Fraser Jones’ plans to build a large-scale facility at his 300-cow farm in Powys were originally approved by the local authority in November 2011, despite a recommendation for refusal by council planning officers.

The matter was discussed again in October 2012 after changes in the council’s constitution and committee membership and the dairy application was rejected.

The Welsh government called in the application in January 2012 prompting a public inquiry hearing held in March this year.

Katie Peerless, the inspector holding the inquiry submitted her report to Welsh ministers with six main points for recommending refusal.

They included: The effect on the character and appearance of the area; slurry spreading and disposal of waste water; the impact on residents of odour, noise and the need for pest control; residents’ health, including children at the local primary school; animal welfare and human rights.

But in a letter explaining his decision Carl Sergeant said that social and environmental implications were outweighed by economic benefits.

Mr Sargeant wrote: “I agree with the inspector that these are relevant issues, but I also consider that the economic aspects of the proposed development are a main consideration in the determination of this application.”

He added: “In my view the weight to be attached to the benefits arising from increased jobs and milk yield should be far more substantial than that afforded to them by the Inspector.

“In my opinion an investment of this size, and the confidence it infers from the business perspective is something to which great weight should be attached.”

The dairy plans include three large buildings, a fodder storage unit, two slurry stores and a water storage tower.

Campaigners opposed to the scheme had said the dairy would be too close to their homes and the school, and objections had been raised about noise, the smell, flies, pollution, increased traffic, the size of the development and its visual impact.

A local action group had been formed to oppose the development.

Owners of Powis Castle – The National Trust – plus the Countryside Council for Wales have also opposed the plans.

On Thursday Simon Pope from the World Society for the Protection of Animals, which gave evidence at the public enquiry, said: “WSPA is incredulous that expert planning advice has now been twice ignored, both at county and national level. “The Planning Inspector recommended the application be rejected on the grounds that the economic benefits are not enough to outweigh the unacceptable harm to tourism, the environment and concerns raised by local residents about the impact on their quality of life and human health.

“However the Minister feels that the possibility of up to ten new jobs is of greater importance, despite a wealth of evidence to show that long term economic sustainability is harmed by the financial drain these types of intensive farms have on their surroundings.

“This is a dark day for Wales and for Welsh dairy farmers, who have protected this beautiful landscape for generations.

“The Inspector felt on balance that this application was contrary to the Welsh Assembly’s own policies on development.

“Having taken part in the Inquiry alongside concerned residents, we worry about the message this sends: if you can provide a handful of jobs, then it seems environmental, animal welfare and economic common sense can be ignored.”

In response to his application being granted, farmer Mr Jones told the BBC that he was delighted and said he always felt he had a good case and that he had put a strong proposal forward.